question about thermometer

I've inherited a thermometer with a car boot lot of wine brew equipment.

The red line is broken i.e one half is one end and the other half is the other end. Is there anyway to get the red marker back to original?

(Hope that makes sense)

Thanks in advance of any help.

Oooh. Going into freezer now.

If i leave it in overnight will it be ok do you think.

Thanks mos